Types of anchor rods

Slotted anchor is a new type of anchor with full length and active reinforcement of surrounding rock. Its solid part is a high-strength steel pipe with longitudinal slits. When installed in a hole slightly smaller than the pipe diameter, it can immediately exert radial pressure and friction on the hole wall to prevent the surrounding rock from sliding down in the whole length range, and with the support of the anchor plate, the surrounding rock is in a three-dimensional stress state. When the surrounding rock is anchored by blasting vibration, the later anchoring force is obviously increased. When the surrounding rock is significantly displaced, the bolt does not lose the supporting resistance, which has better characteristics than the expanded shell bolt.

Main performance and specifications of pipe seam anchor rod

1, main technical performance

(1) initial anchoring force: 3~7 tons;

(2) Pull-off load of pipe ring: 8~ 10 ton;

(3) Tensile fracture capacity of anchor pipe:12 ~13t;

(4) The corrosion resistance is 20-30% higher than that of A3 steel, which is beneficial to long-term use.

2. Specification

(1) outside diameter (mm): φ 30, φ 33, φ 40, φ 43 (0.5).

(2) Length (mm): 1200, 1500,1800,2000,2500.

(Can also be produced according to customer requirements);

(3) Material: 16Mn, 20mnsi

Pipe seam bolt is less used in coal mine now. 1 overview of spin anchor rod spin anchor rod is a kind of spiral anchor rod, which will become the top anchor rod if used reasonably.

Spiral anchor is one of the soft soil anchors developed at the beginning of last century. Because of its simple and fast construction, it is widely used in some field projects or auxiliary anchorage of rock and soil. Professor Hui Xingtian of Xi 'an University of Science and Technology has deeply analyzed the traditional spiral anchor in his long-term research practice and invented a new type of spiral anchor → spin anchor 1999. Spin anchor abandons the large anchor blade structure of traditional spiral anchor, adopts hollow continuous small spiral structure and adopts different construction techniques, which makes the application of spin anchor fundamentally changed. Thus an all-round system with a series of functions is derived. Let's briefly introduce various types of spin anchors.

Self-tapping threaded bolt → self-tapping threaded installation in drilling hole, the anchoring force can reach 70KN without using anchoring agent.

Innovation: full-length anchor bolt without anchoring agent

Advantages: low cost and fast construction speed.

Disadvantages: Installation requires accurate drilling and proper coordination of various parameters. It is difficult to meet the requirements in construction.

Self-tapping extrusion threaded bolt → direct extrusion threaded installation anchoring force 20KN/m soil layer without drilling.

Innovation: Full-length anchor bolt without drilling and grouting.

Advantages: the bearing capacity of soil is greatly improved by squeezing to strengthen the soil structure, and the construction speed is fast and the anchorage is timely;

Disadvantages: the drilling rig requires large torque, limited adaptability, and small unit anchoring force in some cases.

After the jet grouting anchor is installed in the borehole, it becomes a jet grouting anchor with initial anchoring force.

Innovation: Grouting anchor with initial anchoring force and full-length anchorage

Advantages: it has a certain initial anchoring force and is suitable for all kinds of soft rock and soil.

Disadvantages: the grouting procedure takes up time, the construction environment is poor and the speed is limited.

Spin resin anchor rod → When installed in the borehole, the spin anchor rod stirs the resin cartridge into a spin resin anchor rod with initial anchoring force.

Innovation: The resin anchor rod is prestressed immediately after the cartridge is stirred.

Advantages: reliable anchorage and wide adaptability.

Disadvantages: Anchor installation requires special drilling tools.

Self-drilling and self-anchored anchor → putting drill pipe into the hollow of spin anchor to complete drilling and installation at one time, which is a self-drilling anchor with initial anchoring force.

Innovation: Self-drilling anchor has initial anchoring force after once drilling and installation.

Advantages: it has a certain initial anchoring force, and is fast to install, and is suitable for any rock and soil layer.

Disadvantages: Installation requires special drilling tools.

Jet grouting anchor → drilling anchor grouting while spraying in the soil layer, and completing the anchoring force of 35KN/m at one time.

Innovation: One-time drilling and installation of grouting soil anchor.

Advantages: Suitable for loose rock and soil.

Disadvantages: it cannot be used for loose bodies in rock mass fracture zone.

2 Schematic diagram of fully rotating anchor rod

Self-drilling, self-rotating, self-anchoring-suitable for any stratum.

Grouting, shotcreting, rotary shotcreting-effective in any case.

Spin anchor 〓 common anchor+self-drilling anchor+grouting anchor+special anchor.

Ordinary bolt → Spin resin bolt-Spin anchoring and resin anchoring agent act at the same time, and the anchoring is reliable. Construction speed is 30% faster. ※: Pre-stress can be applied

Self-drilling anchor → Self-drilling anchor —— Overcomes the shortcomings of conventional self-drilling anchor, integrates drilling and anchoring, and can complete soft rock mass at one time without grouting. ※:

Simplify working procedures; The efficacy is improved by 50%

Grouting anchor → jet grouting anchor-grout can ensure the grouting fullness between rotating steel wires from the kinetic energy of rotating steel wires, and can also enter the fractured rock mass. The reliability of grouting anchoring effect is 99%. ※

Special anchor → self-tapping screw anchor. Rotary shotcrete anchor rod 〓 No need to drill holes in soft rock and soft soil. ※: Direct extrusion and screwing anchorage; Installation and reinforcement of jet grouting borehole in loose stratum

Anchoring is completed at one time.

3 Spin bolt system 1 Direct self-tapping precession-Self-tapping extrusion precession bolt is equipped with a drill bit, which directly drives the bolt to rotate into the soil. In the precession process, the anchor rod squeezes the soil around the rod body, so that the soil parameters near the rod body are strengthened.

Self-tapping extrusion screw anchor is different from self-drilling anchor, and the anchoring of self-drilling anchor depends entirely on later anchoring grouting, so it is difficult to achieve saturated grouting for upward holes, and the anchoring reliability is poor. After installation, the self-forming anchoring force of the spin anchor rod is completed. The same anchoring force can be guaranteed at any angle.

Applicable conditions of self-tapping extrusion rotary anchor: collapsible loess, silt and loose rock and soil.

2. Self-tapping screw-in hole-Self-tapping screw-in anchor firstly drills holes in the pre-drilled holes, and drives the anchor with a drilling machine, so that the thread of the anchor is engraved into the hole wall during the rotation process, which plays an anchoring role.

The drill pipe is put into the anchor body, and the anchor rod is installed while drilling. Drilling and installation can be completed at one time, which is beneficial to ensure the reliability of anchorage and the construction speed is fast.

Applicable conditions: In any stratum, it is especially suitable for pre-drilling soft and broken rock and soil. Screw the rotary anchor rod into the drilling hole, and grout it in the hollow of the rod body after installation. Part of the slurry fills the rotating space along the rotating thread, and part of the slurry penetrates into the rock mass to reinforce the rock mass, so that the rock mass can be anchored and reinforced at the same time.

Applicable conditions: any stratum, especially suitable for jet grouting anchor rod in soft and broken rock and soil.

In the complex soil layer, grouting is carried out while the anchor rod is screwed in, so that grouting is completed after the installation of rotary jet drilling. The resin anchoring agent is put into the front end of the spin anchor rod, and the resin is pressurized, stirred and extruded during the installation of the spin anchor rod, so that the resin anchoring agent is filled with the spin wire, and both the anchoring agent and the spin wire play an anchoring role.